ellipsis(){
  text-overflow:ellipsis
  white-space:nowrap
  overflow:hidden
}
// 一像素下边框
bottom-border-1px($color)
  position relative
  border none
  &:after
    content ''
    position absolute
    left 0
    bottom 0
    width 100%
    height 1px
    background-color $color

//根据像素比缩放1px像素边框
@media only screen and (-webkit-min-device-pixel-ratio: 2 )
  .border-1px
    &::after //下边框
      transform scaleY(0.5)

@media only screen and (-webkit-min-device-pixel-ratio: 3 )
  .border-1px
    &::after //下边框
      transform scaleY(.33333)







// 一像素上边框
top-border-1px($color)
  position relative
  &::before
    content ''
    position absolute
    z-index 10
    left 0
    top 0
    width 100%
    height 1px
    background-color $color



//根据像素比缩放1px像素边框
@media only screen and (-webkit-min-device-pixel-ratio: 2 )
  .border-1px
    &::before  //上边框
      transform scaleY(0.5)

@media only screen and (-webkit-min-device-pixel-ratio: 3 )
  .border-1px
    &::before //上边框
      transform scaleY(.33333)


//根据像素比来使用 2x图 3x图
bg-image($url)
  background-image: url($url + "@2x.png")
  @media (-webkit-min-device-pixel-ratio: 3),(min-device-pixel-ratio: 3)
    background-image: url($url + "@3x.png")

//清除浮动
clearFix()
    _zoom 1
    &::after
      content: ''
      display: block
      clear: both
      height:0
